Electric spark ignition apparatus for internal-combustion engines



May 12, 1953 J LAIRD 2,638,565

. ELECTRIC SPARK IGNITION APPARATUS FOR INTERNAL-COM TION ENGINES FiledJan. 1950 Patented May 12, 1953 ELECTRIC SPARK IGNITION APPARATUS FORINTERNAL-COMBUSTION ENGINES John Andrew Laird, Coventry, England,assignor to Joseph Lucas Limited, Birmingham, England ApplicationJanuary 24, 1950, Serial No. 140,191 In Great Britain February 7, 1949 6Claims.

This invention has for its object to provide improved electric sparkignition apparatus, of the kind in which a condenser, or each of aplurality of condensers, is charged from a magneto, ignition coil orlike energy source, and subsequently discharged across a sparking plugafter a predetermined voltage has been attained.

The invention comprises a system in which between the energy source, acondenser or condensers, and the sparking plugs, is arranged adistributor adapted to effect charging of the condenser Or eachcondenser across a gap, and to effect discharge across an associatedgap.

In particular, the invention comprises for use in a system as defined inthe preceding paragraph, a distributor consisting in part of a rotarymember adapted to efiect the condenser charging and dischargingoperations across different gaps in the desired sequence.

In the accompanying drawings, Figures 1, 2, 3 and 4 are diagrammaticviews illustrating four typical embodiments of the invention.

In one arrangement as represented in Figure l for producing sparks ateach in turn of four sparking plugs a, there are employed fourcondensers b, each being adapted for connection to a sparking plug. Theenergy required for charging the condensers is supplied by a magneto,ignition coil or the like. In each of the examples illustrated thesource comprises an ignition coil having a primary winding and asecondary winding (2, the primary winding being supplied with currentfrom a battery or dynamo through a conventional interrupter e acrosswhich is connected the usual spark-suppressing condenser f.

In the example shown in Figure l, the connection of each condenser b inturn to the source and the associated sparking plug a is effectedthrough a distributor which comprises a rotary arm 9 adapted to beconnected to one end of the winding (1, and in the distributor arearranged at 90 apart four pairs of stationary electrodes h, a gap beingprovided between each pair. Also the arm 9 (during its rotation)provides a gap between its outer end and one of the electrodes in eachpair 71..

The electrode in each pair with which the rotary arm g co-operates isconnected to one side of a condenser, and the other electrode in eachpair is adapted for connection to an associated sparking plug a. Theother sides of the condensers are connected together and to the otherend of the winding 11.

The arrangement is such that when the rotary arm 9 comes opposite anypair of stationary electrodes h, a charge is given to the associatedcondenser across the gap between the arm and the adjacent electrode, andwhen the voltage of the condenser reaches a predetermined amount, thecondenser is discharged to the associated sparking plug across the gapbetween the said stationary electrode and its neighbouring stationaryelectrode, the action being repeated at each pair of stationaryelectrodes during the rotation of the distributor arm.

In the arrangement shown in Figure 2, a single condenser b is used, andin this case one of each of the stationary electrodes h are connectedtogether and to one side of the condenser. The action is similar to thatabove described, excepting that the one condenser is charged anddischarged each time the arm g comes opposite the stationary electrodesh. To ensure prompt action of each discharge gap between the electrodesh at the appropriate time, it is necessary that when a discharge occursacross the gap between the part g and any of the adjacent stationaryelectrodes h, it should ionise the gap between the stationaryelectrodes. This may be ensured in a variety of ways. formed in each ofone of the electrodes h as shown. But preferably an arrangement as shownin Figure 3 is used.

In this arrangement four pairs of discharge electrodes h are mounted atequal distances apart in an insulating enclosure 2 (two only of whichappear in the diagram), and connected to one in each pair of theelectrodes n is an adjacently arranged fixed electrode a with which thearm 9' co-operates. The condenser b is charged across the gaps between9* and a, and when the condenser is fully charged the discharge betweengand 7 ionises the gap between the adjacent electrodes h, thus ensuringprompt action of the gap between the latter electrodes.

In another embodiment of the invention in which a single condenser isused and as shown in Figure 4, the rotary part of the distributorconsists of an annular screen It having a gap in in its periphery. Atthe centre of the screen is arranged a charging gap formed by a pair ofstationary electrodes n, and around the screen are disposed fourequi-spaced discharging gaps formed by four pairs of electrodes h. Oneof the charging electrodes is connected to one end of .the winding d.The other electrode and one of each of the discharge electrodes h areconnected together and to one side of the condenser b, the other side ofthe condenser being connected to the other end of the winding d. Theother elec- For example a hole may be.

trodes of the discharge gaps are connected to the associated Sparkinggaps a. It will be understood that in this example (as in that shown inFigure 3) there are four pairs of electrodes h and four sparking gaps a.The arrangement is such that the condenser b is caused to be chargedacross the charging gap n when the gap m in the rotary screen 70 isopposite any one of the discharging gaps h, and the spark across thecharging gap serves to ionise the exposed discharging gap, so that thecondenser can discharge across it when the required voltage is reached.

Preferably all the above described means are intended for use in anignition system in which the sparking plugs are adapted'to operate at arelatively low voltage and have a permanent leak between the firing endsof their electrodes, each plug being preferably of the kind in which thefiring ends of its electrodes are flush and are separated by a narrowannulus of insulating material.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. An ignition distributor comprising in combination a plurality ofpairs of fixed electrodes, the electrodes of each pair being separatedby an ionisible gap, and means consisting at least in part of a rotarymember whereby the gaps between said electrodes are exposible insequence to an ionising eifect, said pairs of electrodes being -situatedin spaced relationship about the rotational axis of said rotary member.

2. An ignition distributor comprising in combinati'on a plurality ofpairs of fixed electrodes, the electrodes of each pair being separatedby an ionisibl'e gap, and a rotary arm whereby the gaps between saidelectrodes are exposible in sequence to an ionising effect, said pairsof electrodes being situated in spaced relationship about the rotationalaxis of said arm, so that the latter serves during rotation to form agap between itself and one electrode of each pair in turn.

3. An ignition distributor comprising in cornb-i'nation a pluralityoipairs of 'fixed electrodes, the electrodes of each pair beingseparated by an io'nisible g'a'p, means electrically interconnecting oneelectrode of each pair, and a rotary arm whereby the gaps between saidelectrodes are exposible in sequence to an ionising effect, said pairsof electrodes being s'itnated in spaced relationship about therotational axis of said arm so that the latter serves during rotation toform a gap between itself and each of the electrically interconnectedelectrodes in turn.

4. An ignition "distributor comp-rising in cornbination a plurality ofpairs of fixed electrodes,

the electrodes of each pair being separated by an i-onisible gap, aplurality of additional fixed electrodes situated adjacent to said pairsof electrodes, means electrically connecting said additional electrodesrespectively to one of each of said pairs of electrodes, and a rotaryarm to cooperate with said additional electrodes for sequentiallyexposing the gaps between the first mentioned electrodes to an ionisingeffect, said pairs of electrodes and said additional electrodes beingsituated in spacedrelationship about the rotational axis of said rotaryarm so that the latter serves during rotation to form a gap betweenitself and each of said additional electrodes in turn.

5. An ignition distributor comprising in co2nbin'at'i'on a plurality ofpairs of fixed electrodes, the electrodes of each pair being separatedby an ionisible gap, an additional pair of fixed elec trodes having agap between them and arranged centrally between the other pairs ofelectrodes, and an ap'ertured rotary screen surrounding said additionalelectrodes to *co-operate therewith for sequentially exposing the gapsbetween the first mentioned electrodes to an ionising effect, the firstmentioned pairs of electrodes being situated in spaced relationshiparound the rotational axis of said screen so that the latter servesduring rotation to expose the first mentioned pairs of electrodes inturn to said additional pair of electrodes.

6. An electric spark ignition system comprising in combination aplurality of sparking plugs, a, condenser, a source of electrical energyfor intermittently charging said condenser, electric circuital meansconnecting said condenser to said source and sparking plugs, and adistributor comprising a plurality of pairs of stationary electrodesforming parts of and providin ionisible gaps in said electric circuitalmeans at positions between said condenser and sparking plugs, and meansconsisting at least in part of a rotary member whereby said gaps aresequentially exposible to an ionising effect so that successive chargesreceived by said condenser from said source are discharged across saidgaps in turn, said pairs of electrodes being situated in spacedrelationship around the rotational axis of said relay member.

JOHN ANDREW LAIRD.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,246,822 Shaw et al Nov. 13, 1917 1,418,518 Bell June 6,192.2 1,907,515 Davis May 9, 1933 2,163,055 Olson June 20, 19392,489,780 Hooven l 1- Nov. 29, 1949 2,507,277 Smits i May 9, 1950

